org.apache.lucene.analysis.standard.StandardTokenizer Maven / Gradle / Ivy
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.lucene.analysis.standard;
import java.io.IOException;
import org.apache.lucene.analysis.Tokenizer;
import org.apache.lucene.analysis.tokenattributes.CharTermAttribute;
import org.apache.lucene.analysis.tokenattributes.OffsetAttribute;
import org.apache.lucene.analysis.tokenattributes.PositionIncrementAttribute;
import org.apache.lucene.analysis.tokenattributes.TypeAttribute;
import org.apache.lucene.util.AttributeFactory;
/** A grammar-based tokenizer constructed with JFlex.
*
* This class implements the Word Break rules from the
* Unicode Text Segmentation algorithm, as specified in
* Unicode Standard Annex #29.
*
Many applications have specific tokenizer needs. If this tokenizer does
* not suit your application, please consider copying this source code
* directory to your project and maintaining your own grammar-based tokenizer.
*/
public final class StandardTokenizer extends Tokenizer {
/** A private instance of the JFlex-constructed scanner */
private StandardTokenizerImpl scanner;
/** Alpha/numeric token type */
public static final int ALPHANUM = 0;
/** Numeric token type */
public static final int NUM = 1;
/** Southeast Asian token type */
public static final int SOUTHEAST_ASIAN = 2;
/** Ideographic token type */
public static final int IDEOGRAPHIC = 3;
/** Hiragana token type */
public static final int HIRAGANA = 4;
/** Katakana token type */
public static final int KATAKANA = 5;
/** Hangul token type */
public static final int HANGUL = 6;
/** String token types that correspond to token type int constants */
public static final String [] TOKEN_TYPES = new String [] {
"",
"",
"",
"",
"",
"",
""
};
/** Absolute maximum sized token */
public static final int MAX_TOKEN_LENGTH_LIMIT = 1024 * 1024;
private int skippedPositions;
private int maxTokenLength = StandardAnalyzer.DEFAULT_MAX_TOKEN_LENGTH;
/**
* Set the max allowed token length. Tokens larger than this will be chopped
* up at this token length and emitted as multiple tokens. If you need to
* skip such large tokens, you could increase this max length, and then
* use {@code LengthFilter} to remove long tokens. The default is
* {@link StandardAnalyzer#DEFAULT_MAX_TOKEN_LENGTH}.
*
* @throws IllegalArgumentException if the given length is outside of the
* range [1, {@value #MAX_TOKEN_LENGTH_LIMIT}].
*/
public void setMaxTokenLength(int length) {
if (length < 1) {
throw new IllegalArgumentException("maxTokenLength must be greater than zero");
} else if (length > MAX_TOKEN_LENGTH_LIMIT) {
throw new IllegalArgumentException("maxTokenLength may not exceed " + MAX_TOKEN_LENGTH_LIMIT);
}
if (length != maxTokenLength) {
maxTokenLength = length;
scanner.setBufferSize(length);
}
}
/** Returns the current maximum token length
*
* @see #setMaxTokenLength */
public int getMaxTokenLength() {
return maxTokenLength;
}
/**
* Creates a new instance of the {@link org.apache.lucene.analysis.standard.StandardTokenizer}. Attaches
* the input to the newly created JFlex scanner.
* See http://issues.apache.org/jira/browse/LUCENE-1068
*/
public StandardTokenizer() {
init();
}
/**
* Creates a new StandardTokenizer with a given {@link org.apache.lucene.util.AttributeFactory}
*/
public StandardTokenizer(AttributeFactory factory) {
super(factory);
init();
}
private void init() {
this.scanner = new StandardTokenizerImpl(input);
}
// this tokenizer generates three attributes:
// term offset, positionIncrement and type
private final CharTermAttribute termAtt = addAttribute(CharTermAttribute.class);
private final OffsetAttribute offsetAtt = addAttribute(OffsetAttribute.class);
private final PositionIncrementAttribute posIncrAtt = addAttribute(PositionIncrementAttribute.class);
private final TypeAttribute typeAtt = addAttribute(TypeAttribute.class);
/*
* (non-Javadoc)
*
* @see org.apache.lucene.analysis.TokenStream#next()
*/
@Override
public final boolean incrementToken() throws IOException {
clearAttributes();
skippedPositions = 0;
while(true) {
int tokenType = scanner.getNextToken();
if (tokenType == StandardTokenizerImpl.YYEOF) {
return false;
}
if (scanner.yylength() <= maxTokenLength) {
posIncrAtt.setPositionIncrement(skippedPositions+1);
scanner.getText(termAtt);
final int start = scanner.yychar();
offsetAtt.setOffset(correctOffset(start), correctOffset(start+termAtt.length()));
typeAtt.setType(StandardTokenizer.TOKEN_TYPES[tokenType]);
return true;
} else
// When we skip a too-long term, we still increment the
// position increment
skippedPositions++;
}
}
@Override
public final void end() throws IOException {
super.end();
// set final offset
int finalOffset = correctOffset(scanner.yychar() + scanner.yylength());
offsetAtt.setOffset(finalOffset, finalOffset);
// adjust any skipped tokens
posIncrAtt.setPositionIncrement(posIncrAtt.getPositionIncrement()+skippedPositions);
}
@Override
public void close() throws IOException {
super.close();
scanner.yyreset(input);
}
@Override
public void reset() throws IOException {
super.reset();
scanner.yyreset(input);
skippedPositions = 0;
}
}